Solar assisted heat pump pilot plant management and troubleshooting by means of numerical modelling: a case study

Abstract

A solar assisted heat pump integrated with fossil burners provides the space heating and Domestic Hot Water (DHW) demand of the sport palace Palacus, Genoa. The plant complexity requires a Data Acquisition System (DAS) to perform diagnoses for problem troubleshooting. A DAS with a set of sensors able to measure every key parameter of the plant loses economic feasibility as the installation complexity increases. This compulsory lack of information can be handled with numerical modelling calibrated on the collected data. In the case study, a net variation in the thermal losses during night (where all the plant is off and the facility is closed) within the DHW storage tanks has been measured. Without any apparent reason, the temperatures reached within the tank at 8.00 a.m. can be either 33 °C or 50 °C. According to the approach of inverse heat transfer problems, a numerical simulation in TRNSYS17 is used to enquire the most likely causes of failure and to establish new regulation criteria. Thermal stratification and its destruction are studied to better understand the temperature trend in the DHW tanks.

Optimisation strategies for solar assisted heat pumps coupled to traditional thermal fields

“…A simplified numerical model of the plant described has been implemented in TRNSYS environment (Figure 2). Despite of the data acquired by the DAS, a numerical modelling still plays a key role in plant optimisation since it allows the choice of the optimal configuration among the different virtual The validation for most of components has been retrieved by the authors' previous work [8] while the missing information has been integrated with the technical datasheets and the measured values. In particular, the working of the numerical model for the solar panels has been validated under different measured climatic conditions (e.g.…”

“…In particular an upper and a lower deadbands (5 °C and 1 °C) control the activation and the stop of the solar pump. In the end, the physical properties of the cold side storage have been chosen basing on the results of [8]. As a first approximation, no thermal losses between the solar field and the cold side storage have been assumed, since the gradient in temperature between the water inside the circuit and the external environment are on average small.…”